1. Technical Field
The present invention relates generally to wireless systems and in particular to multi-carrier wireless systems. Still more particularly, the present invention relates to a method and system for implementing a service driven air interface protocol for multi-carrier wireless systems.
2. Description of the Related Art
Code Division Multiple Access (CDMA) cellular communications networks are commonly utilized to provide wireless communication service to mobile users. At its infancy, CDMA networks utilized a single frequency carrier to provide service to the mobile units, base stations, and other units in the service area. Substantial increases in the utilization of cellular communication equipment, such as wireless enabled laptop computers and Third Generation (3G) high rate mobile terminals, resulted in a need for even higher bandwidth (i.e., more frequencies) within the service area than could be supported by the single frequency carrier.
This need for higher bandwidth led to the development of a multi-carrier air interface. Multi-carrier networks utilize several different frequency ranges in the available frequency spectrum for wireless communication. Thus, a first frequency range is utilized for a first carrier, a second frequency range is utilized for a second carrier, and so on. Each carrier frequency has an associated capacity, which limits the total amount of traffic (i.e., the load) allowed on that carrier.
Traditionally, cellular telephone networks provided service for voice users only and did not address high-speed data (HSD) applications such as electronic mail, with large multimedia attachments, facsimile, image transmission, and FTP transfer.
The wireless industry has experienced increasing demands for wireless services include voice, real-time and delay tolerant data applications. For example, the Telecommunications Industry Association (TIA) TR-45.5 cellular CDMA standard committee has developed CDMA networks that can support high-speed data (HSD) along with conventional voice telephony. These different types of services typically have different Quality of Service (QoS) requirements.
With the increase of both voice and data traffic, multi-carrier deployments provide a practical way to handle increased traffic. However, efficient traffic distribution among multi-carrier frequencies have proven to be a hurdle for CDMA networks. Thus, the wireless industry is searching for the next generation CDMA systems that can provide a rich portfolio of services to its end users cost-effectively. A number of proposals have been submitted to different standards organizations worldwide for this goal. In particular, the Third Generation Partnership Project 2 (3GPP2) is currently developing a 1xEV-DV solution that will provide both voice and high speed data services in a single (1.25 MHz) spread spectrum carrier. Because of the bandwidth limitation, however, those systems that are being proposed in a single 1.25 MHz carrier will not satisfy the industry need in terms of the peak data rate offered, overall system capacity, as well as required cost-effective QoS solutions throughout the cell/sector coverage.
One reason for the limitation in the proposed solution is the current data communication protocol design utilized to implement most communication networks including wireless networks.
FIG. 6 illustrates a protocol stack configuration. As shown, mobile station 102 communicates with base station 108 over a radio interface 602 by utilizing a series of communication protocols broken down into three distinct layers. Layer 1 of the protocol stack is the physical layer. The physical layer is concerned with the transmission of unstructured bit streams over a physical link, involving such parameters as transmit power, signal bit/chip waveform and so forth. In this illustration, the physical layer operates in accordance with IS2000 and its subsequent Layer 2 of the protocol stack is the data link layer. The data link layer provides the reliable transfer of data across the physical link, such as sending blocks of data with the necessary synchronization, error control, flow control, and so forth. As currently defined, IS2000 utilizes a radio link protocol defined by IS-707 for the data link layer operations. Layer 3 of the protocol stack is the network layer. The network layer provides upper layers with independence from the data transmission and switching technologies used to connect systems. The network layer is responsible for establishing, maintaining and terminating connections. In this embodiment of the invention, the network layer operates in accordance with any network layer protocol suitable for use with IS2000.
Particularly relevant to the actual transmission of packets are these lower layers, which include layers 2 and 3 that interact with the physical layer (i.e., the underlying radio connection) to transmit and receive communication between the mobile device and base stations. The particular carriers available are defined within these protocol layers and are utilized during the communication. For example, in the conventional multi-carrier system, e.g. 3xRTT, the mobile device always transmits/receives on a fixed number of carriers in a rigid manner. (i.e., the type of communication supported by each carrier cannot be changed). These systems cannot support dynamic switching and allocation of carriers because the layer 2 and 3 protocol design do not support flexible carrier(s) switching and allocation to satisfy different service requirements.
The present invention thus realizes that it would be desirable to provide a wireless system and protocol layer configuration that enables flexible carrier assignment and resource allocation. A wireless system and protocol configuration that supports dynamic and smooth transition from one physical layer configuration to another based on quality of service requirements, loading conditions, and channel conditions would be a welcomed improvement. It would be further channel conditions would be a welcomed improvement. It would be further desirable to provide a wireless system and protocol configuration that enables a mobile station to flexibly receive/transmit from/to different numbers of carriers at different time instants. These and other benefits are provided by the present invention.